Sift flour, salt, baking powder and baking soda together and set aside. Beat butter and cream cheese together at medium speed until combined and pale - add sugar and beat further on. Add eggs, one at a time. Beat until combined at each addition. Add vanilla and lime zest - then lower the speed and add flour. Mix well and transfer the cake mixture to the pan. Tap the side a few times to get rid of excess air bubbles. Bake for 45 minutes - if the top starts to get too dark - cover loosely with foil.

When the cake is done - rest for 10 minutes before removing from the tin. Serve with sour cream or whip cream and lime zest.